1. Field of the Invention
The present invention relates to a fuel cell and more particularly to proton exchange membrane fuel cell (PEMFC).
2. Description of Related Art
A proton exchange membrane fuel cell (PEMFC) includes a membrane electrode assembly (MEA), and the MEA includes a proton exchange membrane (PEM) and two electrode layers. The two electrode layers include an anode layer and a cathode layer. Furthermore, the two electrode layers are disposed on each side of the PEM. Fuel (such as methanol or hydrogen) for the anode layer reacts with a catalyst to generate hydrogen ions and electrons. The hydrogen ions pass through the PEM to the cathode layer, and the electrons pass through a circuit to the cathode layer. Next, the hydrogen ions and electrons react with the catalyst and oxygen in the cathode layer to generate water. Meanwhile, the traveling of the electrons forms a usable electric current.
It should be noted that the conventional fuel cell generally uses a fan or a pump to continuously transport anode reactant (such as methanol or hydrogen) to the surface of the anode layer and cathode reactant (such as oxygen) to the surface of the cathode layer respectively. As a result, the fuel cell is able to generate electricity continuously. However, because the fan and the pump consume some of the electrical energy generated by the fuel cell, the actual output energy from the fuel cell is lower. Furthermore, the fan and the pump are driven by electricity; the reliability and life span thereof are lower so that overall reliability and life span of the fuel cell are affected.
In addition, the rotating speeds of the fan and the pump have to be carefully controlled through a control element so as to match the amount of electrical power produced by the fuel cell. Consequently, a rather complicated circuit control of the conventional fuel cell is required.